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WHEN DOES AN ELECTRICAL SHOCK BECOME FATAL?

In this age of electricity and electric wires carrying currents of various intensity, the question of danger arising from contact with them has caused considerable discussion. An examination into the facts as they exist may therefore enlighten some who are at present in the dark.

To begin with, we often hear the question asked—why is it that certain wires carrying very large currents give very little shock, whereas others, with very small currents, may prove fatal to those coming in contact with them? The answer to this is—that the shock a person experiences does not depend upon the current flowing in the wires, but upon the current diverted from them and flowing through the body.

The muscular contraction due to a galvanic current, which was first observed in the frog, gives a good illustration of the fact that it requires only a very minute current to flow through the muscles in order to contract them. Thus the simple contact of pieces of zinc and copper with the nerves generated current sufficient to excite the muscles—a current which would require a delicate galvanometer for its detection. What is true of the muscles of the frog holds good also for the human muscles; they too are very susceptible to the passage of a current.

In order to determine the current which proves fatal we need only to apply the formula which expresses Ohm's law, viz., C=E/R, or the current (ampere) equals the electromotive force (volt) divided by the resistance (ohm).

According to the committee of Parliament investigation, the electromotive force dangerous to life is about 300 volts; this then is the quantity, E, in the formula. There remains now only to determine the resistance in ohms which the body offers to the passage of the current. In order to obtain this, a series of measurements under different conditions were made. On account of the nature of the experiment a high resistance Thomson reflecting galvanometer was used, with the following results.

When the hands had been wiped perfectly dry, the resistance of the body was about 30,000 ohms; with the hands perspiring ordinarily it fell to 10,000 ohms; whereas when they were dripping wet it was as low as 7,000 ohms. Our readers can judge this resistance best when we state that the Atlantic cable offers a resistance of 8,000 ohms.

Taking an ordinary condition of the body, with the hands perspiring as usual, we would have the resistance equal to 10,000 ohms. Applying the two known quantities in the formula, we get:

C = (300 / 10,000) - (1 / 33.333+)

This means, therefore, that when the electromotive force or potential is great enough to send a current of 1/33 ampere through the body, fatal results will ensue. This current is so minute that it would deposit only about 6 grains of copper in one hour, a grain being 1/7,000 of a pound.

Let us now compare these figures with some actual cases, taking as an example a system of incandescent lighting. In these systems the difference of potential between any two points of the circuit outside of the lamps does not exceed 150 volts. Taking this figure, therefore, it will be seen that under no circumstances can the shock received from touching these wires become dangerous—not even by touching the terminals of the dynamo itself; because in neither case can a current be driven through the body, sufficient to cause an excessive contraction of the muscles.

In a system of arc lighting, however, we have to deal with entirely different conditions; for, while in the incandescent system the adding of a lamp, which diminishes the resistance, requires no increase of electromotive force, the contrary is the case in the arc light system. Here every additional lamp added to the circuit means an increase in resistance, and consequent increase in electromotive force or potential. Taking for example a well known system of arc lighting, we find that the lamps require individually an electromotive force of 40 volts with a current of 10 amperes. In other words, the difference in potential at the two terminals of every such lamp is 40 volts. Consequently, if the circuit were touched in two places, including between them only one lamp, no injurious effects would ensue. If we touch the circuit so as to include two lamps between us, the effect would be greater, since the potential between those two points is 2 x 40 volts. We might continue in this manner touching the circuit until we had included about 7 or 8 lamps, when the shock would become fatal, since the point would be reached at which the difference of potential is great enough to send a dangerous current through the body.

Up to this point we have assumed that, while touching two points in the wire, the rest of the circuit is perfectly insulated, so that no current can leak, in other words, that the circuit is nowhere "grounded." If this is not the case we may, under suitable conditions, receive a shock by touching only one point of the wire. This becomes clear by considering the current to leak from another spot of different potential, to pass through the ground and into the body; thus, on touching the wire the body virtually makes a connection between the two points of the circuit. In clear dry weather such leaks are insignificant; but in damp and rainy weather, and with poor insulation, they may rise to such a point at which it would be dangerous to touch the circuit even with one hand, the leaks being sometimes so great as to cause the lamps to burn in a fitful, desultory manner, and to go out entirely.

There is still another factor which enters into the discussion of the danger of electric light wires. This must be looked for in the fact that the physiological effects are greatest at the moment of the opening or the closing of the circuit; or in a closed circuit they are the more marked when the flow of current stops and starts, or diminishes and increases. In dynamo electric machines the current is not absolutely continuous or uniform, since the coils on the armature being separated a distance cause a slight break or diminution of the current between each. This break is so short that it does not interfere with the practical work for lighting; in some constructions, nevertheless, the distances apart is so great that, while not interfering with light, its effects upon the muscles are greatly increased over those of other constructions which give a more uniform current.

All these statements might lead to the conclusion that arc light wires are dangerous under any circumstances; but this is not the case. The first and only requisite is, that they be perfectly insulated. When thus protected accidents from them are impossible, and all mishaps that have occurred through them can be traced directly to the lack of insulation. Nevertheless, we would warn our readers against experimenting upon arc wires by actual trial, because unforeseen conditions might lead to disagreeable results.

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ROBERT CAUER'S STATUE OF LORELEI.

The statue of Lorelei, the mythical siren of the Rhine, represented in the annexed cut, which is taken from the Illustrirte Zeitung, was modeled by Robert Cauer, of Kreuglach on the Rhine. He was born at Dresden in 1831, and is the son of the well-known sculptor Emil Cauer, and a brother of the sculptor Karl Cauer.



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REDUCING AND ENLARGING PLASTER CASTS.

Ordinary casts taken in plaster vary somewhat, owing to the shrinkage of the plaster; but it has hitherto not been possible to regulate this so as to produce any desired change and yet preserve the proportions. Hoeger, of Gmuend, has, however, recently devised an ingenious method for making copies in any material, either reduced or enlarged, without distortion.

The original is first surrounded with a case or frame of sheet metal or other suitable material, and a negative cast is taken with some elastic material, if there are undercuts; the inventor uses agar-agar. The usual negative or mould having been obtained as usual, he prepares a gelatine mass resembling the hektograph mass, by soaking the gelatine first, then melting it and adding enough of any inorganic powdered substance to give it some stability. This is poured into the mould, which is previously moistened with glycerine to prevent adhesion. When cold, the gelatine cast is taken from the mould, and is, of course, the same size as the original. If the copy is to be reduced, this gelatine cast is put in strong alcohol and left entirely covered with it. It then begins to shrink and contract with the greatest uniformity. When the desired reduction has taken place, the cast is removed from its bath. From this reduced copy a cast is taken as usual. As there is a limit to the shrinkage of the gelatine cast, when a considerable reduction is desired the operation is repeated by making a plaster mould from the reduced copy, and from this a second gelatine cast is taken and likewise immersed in alcohol and shrunk. It is claimed that even when repeated there is no sacrifice of the sharpness of the original.

When the copy is to be enlarged instead of reduced, the gelatine cast is put in a cold water bath, instead of alcohol. After it has swollen as much as it will, the plaster mould is made as before. For enlarging, the mould could also be made of some slightly soluble mass, and then by filling it with water the cavity would grow larger, but it would not give so sharp a copy.

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STRIPPING THE FILM FROM GELATINE NEGATIVES.

We have frequent inquiries as to the best means of removing a gelatino-bromide negative from its glass support so that it can be used either as a direct or reversed negative, and it does not appear to be very generally known that about two years ago Mr. Plener described a method which answers well under all circumstances, whether a substratum has been used or not.

If a negative is immersed in extremely dilute hydrofluoric acid contained in an ebonite dish, say half a teaspoonful to half a pint of water, the film very soon becomes loosened, and floats off the glass, this circumstance being due to the solvent action which the acid exercises upon the surface of the plate as soon as it has penetrated the film. If the floating film be now caught upon a plate which has been slightly waxed, and it is allowed to dry on this plate, it will become quite flat and free from wrinkles. To wax the plate, it should be held before the fire until it is moderately hot, after which it is rubbed over with a lump of wax, and the excess is polished off with a piece of flannel. When the film is dry, it will leave the waxed glass immediately, if one corner is lifted by means of a penknife. The film will become somewhat enlarged during the above-described operation; but, by taking suitable precautions, this enlargement may be avoided. It is also convenient to prepare the hydrofluoric acid extemporaneously by the action of sulphuric acid on fluoride of sodium; and, in many cases, it is advisable to thicken up the film by an additional layer of gelatine.

The following directions embody these points. The negative, which must be unvarnished, is leveled, and covered with a layer of warm gelatine solution (one in eight) about as thick as a sixpence. This done, and the gelatine set, the plate is immersed in alcohol for a few minutes in order to remove the greater part of the water from the gelatinous stratum. The next step is to allow the plate to remain for five or six minutes in a cold mixture of one part of sulphuric acid with twelve parts of water, and in the mean time two parts of sodium fluoride are dissolved in one hundred parts of water, an ebonite tray being used. A volume of the dilute sulphuric acid equal to about one-fourth of the fluoride solution is next added from the first dish, and the plate is then transferred to the second dish, when the film soon becomes liberated. When this is the case, it is placed once more in the dilute sulphuric acid. After a few seconds it is rinsed in water, and laid on a sheet of waxed glass, complete contact being established by means of a squeegee, and the edges are clamped down by means of strips of wood held in position by American clips or string. All excess of sulphuric acid may now be removed by soaking the plate in methylated alcohol, after which it is dried. It is as well to add a few drops of ammonia to the last quantity of alcohol used.

The plate bearing the film negative is now placed in a warm locality, under which circumstances a few hours will suffice for the complete drying of the pellicular negative, after which it may be detached with the greatest ease by lifting the edges with the point of a penknife.—Photo. News.

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NEW ANALOGY BETWEEN SOLIDS, LIQUIDS, AND GASES,

By W. SPRING.

The author asks in the first place, What is the cause of the different specific gravities of one and the same metal according as it has been cast, rolled, drawn into wire, or hammered? Does the difference observed prove a real condensation of the matter under the action of pressure, or is it merely due to the expulsion by pressure of gases which have been occluded when the ingot was cast? According to well-known researches, metals such as platinum, gold, silver, and copper, which have been proved to occlude gases on fusion, and to let them escape, incompletely, on solidification, are precisely those which are most increased in their specific gravity by pressure. The author has submitted to pressures of about 20,000 atmospheres metals which possess this property, either not at all, or to a very trifling extent, and he finds that though a first pressure produces a slight permanent increase of density, its repetition makes little difference. Their density is found to have reached a maximum. Hence the density of solids, like that of liquids, is only really modified by temperature. Pressure effects no permanent condensation of solid bodies, except they are capable of assuming an allotropic condition of greater density. The author's former researches tend to show that solid matter, in suitable conditions of temperature, takes the state corresponding to the volume which it is compelled to occupy. Hence there is an analogy between the allotropic states of certain solids and the different states of aggregation of matter. Possibly the different forms of matter may be due to a single cause—polymerization. The limit of elasticity of a solid body is the critical moment when the matter begins to flow under the action of the pressure to which it is submitted, just as, e.g., ice at or below 0 deg. may be liquefied by strong pressure. A brittle body is simply one which does not possess the property of flowing under the action of pressure.

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HYDROGEN AMALGAM.

Hydrogen, although a gas, is recognized by chemists as a metal, and when combined with any solid metal—as in the case known to electricians as the polarization of a negative element,—the compound may correctly be termed an alloy; while any compound of hydrogen with the fluid metal mercury may with equal correctness be termed an amalgam of hydrogen, or "hydrogen amalgam." The efforts of many chemists and mining engineers have for many years been devoted to a search for some effective and economical means for preventing the "sickening" of mercury and its consequent "flouring" and loss. Some sixteen or more years ago, Professor Crookes, F.R.S., discovered and, after a series of experiments, patented the use of an amalgam of the metal sodium for this purpose. He made the amalgam in a concentrated form, and it was added in various proportions to the mercury used for gold amalgamation. Water becoming present, it will readily be understood that the sodium, in being converted into the hydrate (KHO) of that metal, caused a rapid evolution of hydrogen. The hydrogen thus evolved was the excess over a certain proportion which enters into combination with the mercury. While the mercury retained the charge of hydrogen, the "quickness" of the fluid metal was preserved; but upon the loss of the hydrogen the "quickness" ceased, and the mercury was acted upon by the injurious components contained in the ore.

Since the introduction of the sodium amalgam, many attempts have been made, more especially in America, to overcome the tendency of mercury to "sicken" and lose its "quickness." The greater number of these efforts have been made by the use of electricity as the active agent in attaining this end; but such efforts have been generally of a crude and unscientific character. Latterly Mr. Barker, of the Electro-amalgamator Company, Limited, has introduced a system—already detailed in these pages—by which the mercury is "quickened." In his method the running water passing over the tables, or other apparatus of a similar character, is used as the electrolyte. In this arrangement, the mercury being the cathode, plates or wires of copper constituting anodes are brought into contact with the water passing over the mercury in each "riffle." Both the cathode and the anodes are, of course, maintained in contact with the poles of a suitable source of electrical supply. The current then passes from the copper anode through the running water to the mercury cathode, and so on to the negative pole of the electro-motor. As a consequence of this arrangement, hydrogen is evolved from the water, and has the effect of reducing any oxide or other detrimental compound of the metal; in other words, it "quickens" and prevents "sickening" of the fluid metal, and consequent "flouring" and loss. While the hydrogen is evolved at the cathode, oxygen enters into combination with the copper constituting the anodes. This to some extent impairs the conductivity of the circuit.

The latest process, however, is that of Mr. Bernard C. Molloy, M.P., which we have already characterized as highly scientific and effective, the production of a suitable amalgam being obtained under the most economical and simple conditions. This process has the advantage of producing not only a hydrogen amalgam, but also at will an amalgam of hydrogen combined with any metal electro-positive to this latter. Thus hydrogen potassium or hydrogen sodium can be obtained, as will be seen by the following description.

Mr. Molloy's effort appears to have been, in the first place, directed to a system which could be adapted to any existing apparatus, and in certain cases where water was scarce, to avoid altogether the use of that, in some districts, rare commodity. For the purpose of explanation we select an ordinary amalgamating table fitted with mercury riffles. The surface of the table is in no way interfered with or disturbed. The bed of the riffle, however, is constructed of some porous material, such as leather, non-resinous wood, or cement, which serves as the diaphragm upon which the mercury rests, and separates the fluid metal from the electrolyte beneath. Running the full length of the table is a thin layer of sand, supported and pressing against the diaphragm, and lying in this sand is the anode, formed preferably of lead. A peroxide of that metal is formed by the action of the currents, and may be readily reduced for use over and over again after working for from one to three months. The peroxide of lead, as is well known, is a conductor of electricity, and this fact constitutes an important advantage in the working of the process. The thin layer of sand is saturated with an electrolyte, such as dilute sulphuric acid (H_{2}SO_{4} + 20H_{2}O) to give a simple hydrogen amalgam; (Na_{2}SO_{4} + xH_{2}O) to give a hydrogen sodium amalgam; or (K_{2}SO_{4} + xH_{2}O) to give a hydrogen potassium amalgam. Numerous other electrolytes constituted by acids, alkalies, and salts can be used to form an amalgam permanently maintained in a condition of "quickness" and freed from all liability to "sicken," whatever the components of the ore may be. The mercury is connected with the negative pole of the voltaic battery or other electro-motor, and the lead made with the positive pole of the same source. When the current passes there is formed according to the nature of the electrolyte, a hydrogen amalgam, or an amalgam of hydrogen with a metal electro-positive to hydrogen. The electrolyte, which, it will be understood, is distinct and apart from the body of water passing over the table, will last almost indefinitely, there being no consumption of any of its constituents, excepting hydrogen and oxygen from the water of solution. The quantity of acid or saline material contained in the electrolyte is so very small that there can be no difficulty in finding a supply in any district. The question of the supply of electricity is one which in many mining districts involves considerations of practical importance, since a large supply would necessitate water or steam power. It has been found that two cells having an electromotive force of about two volts each will in this process suffice; if preferred, however, a very small dynamo machine can be used. In connection with the electro-motive force it is requisite to use, it may be observed that an amalgam of sodium containing only a small quantity of this metal would, when constituting a positive element in conjunction with a lead negative and on an aqueous electrolyte, give an opposing electro-motive force of less than three volts. Such an amalgam could therefore be obtained under an electro-motive force of about four volts. The electrical resistance in the circuit constituted by the apparatus being very small, no electrical power is wasted. When water constitutes the electrolyte, as in Barker's system, then the electro-motive force required to obtain a given current would be very much greater than that above specified. The conditions assured under this process appear to be all that can be required, while the amalgams obtained are those most calculated to preserve the "quickness" and prevent the "sickening" of the mercury.

Mr. Molloy has designed a special form of amalgamating machine to be used in conjunction with the above process, and with or without the aid of water. By the employment of this machine, each particle of the ore is slowly rolled in the quickened mercury for from fifteen to thirty or more seconds.

When the extent of the gold and silver mining industries is considered, and when it is borne in mind that a considerable percentage of the precious metal present in the ore is, in the ordinary process of extraction, lost through defective amalgamation—due to insufficient contact with the mercury or to a total absence of contact, as in the case of float gold—it is obvious that the introduction of any system obviating such loss is a matter of very great importance to those who are interested in the above mentioned industries. We expect shortly to hear of the practical introduction on a large scale of Mr. Molloy's process, and we look forward with interest to the results which may be obtained from it.—The Engineer.

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TREATMENT OF ORES BY ELECTROLYSIS.

By M. KILIANI.

The author lays down general principles for electrolytic metallurgy. Ores must be distinguished as good and bad conductors; the former may serve directly as anodes, and are easily oxidized by the electro-negative radicals formed at their contact, and dissolve readily in the electrolyte. The bad conductors have to be placed in contact with a conducting anode, formed of an inoxidizable substance, such as platinum, manganese peroxide, or coke. In laboratory experiments a good conducting ore is electrolyzed by suspension from a platinum wire in connection with the source of electricity, and is then immersed in the bath. On an industrial scale the ore, coarsely broken up, is placed in one of the compartments of a trough divided by a diaphragm.

On the fragments of the ore which extend up outside of the electrolytic bath is laid a plate of copper connected with the positive wire. Care must be taken that this plate does not plunge into the bath, otherwise the current would not traverse the ore at all. The cathode is preferably formed of the same metal which is to be obtained. The bath should not contain organic acids. In practice the common mineral acids are employed, or their salts, selecting by preference a salt of the metal which is to be isolated. It is convenient to pass the current through the greatest possible number of small decomposition troughs, taking care that the resistance in each is not too great. With a current of one and the same intensity we obtain in n troughs n times as much metal as in a single one. To keep down the resistance of the circuit we employ poles of a large surface, i.e., plenty of ore and baths which are as good conductors as possible.

The state in which the metal is deposited at the negative pole depends on the secondary actions undergone by the electrolyte, and especially of the escape of gas. This is a function of the density, of the current, i.e., the proportion of its intensity to the surface of the cathode. If the density is too great there is an escape of hydrogen, and the metal is deposited in a spongy condition. If the density of the current falls below a certain minimum, an oxide is deposited in place of metal. The electrolytic treatment of ores often renders it possible to separate the different metals which may be present. These are deposited in succession, and are sharply separated if the electromotive power is not too great.

1. Zinc.—The zinciferous compounds—calamine, blende, and zinc ash—are all poor conductors. They are first dissolved, and the salts obtained are electrolyzed, employing anodes of coke. Blende should be roasted before it is dissolved. The electrolytic bath should be as concentrated as possible to avoid sponginess of the metal and an escape of hydrogen. In a saturated solution the formation of hydrogen decreases as the density of the current augments.

2. Lead.—Galena is a good conductor, and may be directly electrolyzed. The best bath is a solution of lead nitrate. The arborescent crystallizations extend rapidly, and must be broken from time to time to prevent the formation of a metallic connection between the anode and the cathode. The sulphur of the galena falls to the bottom of the bath, and may be separated from the gangue by solution in carbon disulphide.

3. Copper.—Native copper sulphide, though a good conductor, cannot be directly electrolyzed en account of the presence of iron sulphide, whence iron would be deposited along with the copper. The copper pyrites are roasted, dissolved in dilute sulphuric acid, and the liquid thus obtained is submitted to electrolysis.

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A PEOPLE WITHOUT CONSUMPTION, AND SOME ACCOUNT OF THEIR COUNTRY—THE CUMBERLAND TABLELAND.

By E. M. WIGHT, M.D., Chattanooga, Tenn., Late Professor of Diseases of the Chest and State Medicine, Medical Department University of Tennessee; Late Member of the Tennessee State Board of Health, and ex-President of the Tennessee State Medical Society.

During the ten years that I have practiced medicine in the neighborhood of the Cumberland Tablelands, I have often heard it said that the people on the mountains never had consumption. Occasionally a traveling newspaper correspondent from the North found his way down through the Cumberlands, and wrote back filled with admiration for their grandeur, their climate, their healthfulness, and almost invariably stated that consumption was never known upon these mountains, excepting brought there by some person foreign to the soil, who, if he came soon enough, usually recovered. Similar information came to me in such a variety of ways and number of instances, that I determined some four years ago, when the attempt to get a State Board of Health organized was first discussed by a few medical men of our State, that I would make an investigation of this matter. These observations have extended over that whole time, and have been made with great care and as much accuracy as possible, and to my own astonishment and delight, I have become convinced that pulmonary consumption does not exist among the people native and resident to the Tablelands of the Cumberland Mountains.

In the performance of the work which has enabled me to arrive at this conclusion, I have had the generous assistance of more than twenty physicians, who have been many years in practice in the vicinity of these mountains. Their knowledge of the diseases which had occurred there extended over a, period of more than forty years. Some of these physicians have reported the knowledge of the occurrence of deaths from consumption on the Tablelands, but when carefully inquired into they have invariably found that the person dying was not a native of the mountains, but, a sojourner in search of health. In answer to the question: "How many cases of pulmonary consumption have you known to occur on Walden's Ridge, among the people native to the mountains?" eleven physicians say, "Not one." All of these have been engaged in practice there more than three years, four of them more than ten years, one of them more than twenty, and one of them more than forty years. All the physicians of whom inquiries have been made are now residents, or have been, of the valleys contiguous to Walden's Ridge, and know the mountain people well. Four other physicians in answer to the same question say, that they have known from one to four cases, numbering eleven in all, but had not ascertained whether five of them were born and raised on the mountains or not. The names and place of death of all these cases were given, and I have traced their history and found that but three of them were "natives," or had lived there more than five years, and that one of these was 57 years of age when she died, and had suffered from cancer for three years before her death. The two others died within six months after returning home from long service in the army, where both contracted their disease.

All these investigations have been made with more particular reference to that part of the Cumberlands known as Walden's Ridge than to the mountains as a whole. This ridge is of equal elevation and of very similar character to the main Cumberland range in the southern part of Tennessee, northwest Georgia, and northwest Alabama, and what is true of this particular part of the great Cumberland table is, in the main, true of the remainder.

Sequatchee Valley lies between Walden's Ridge and what is commonly known in that neighborhood as the Cumberland Mountains, and separates it from the main range for a distance of about one hundred miles, from the Tennessee River below Chattanooga to Grassy Cove, well up toward the center line of the State. Grassy Cove is a small basin valley, which was described to me there as a "sag in the mountains," just above the Sequatchee Valley proper. It is here that the Sequatchee River rises, and flowing under the belt of hills which unites the ridge and the main range, for two miles or more, rises again at the head of Sequatchee Valley. Above Grassy Cove the mountains unite and hold their union firmly on their way north as far as our State reaches.

Topographically considered as a whole, the Cumberland range has its southern terminus in Alabama, and its northern in Pennsylvania. It is almost wholly composed of coal-bearing rocks, resting on Devonian strata, which are visible in many places in the valleys.

But a small portion of the Cumberland lies above a plane of 2,000 feet. Walden's Ridge and Lookout Mountain vary in height from 2,000 to 2,500 feet.

North of Grassy Cove, after the ridges are united, the variation from 2,000 feet is but little throughout the remainder of the State, and the general character of the table changes but little. The great and important difference is in the climate, the winters being much more severe in these mountains in the northern part of the State than in the southern, and the summers much more liable to sudden changes of weather. Scott, Fentress, and Morgan counties comprise this portion of the table, and these have not been included in my examination, excepting as to general features.

In all our southern country, and I may say in our whole country, there is no other large extent of elevated territory which offers mankind a pleasant living place, a comfortable climate—none too cold or too hot—and productive lands. We have east of the upper waters of the great Tennessee River, in our State, and in North Carolina and Georgia, the great Blue Ridge range of mountains, known as the Unaka, or Smoky, Chilhowee, Great and Little Frog, Nantahala, etc., all belonging to the same family of hills. This chain has the same general course as the Cumberlands. It is a much bolder range of mountains, but it is vastly less inhabitable, productive, or convenient of access. The winters there are severely cold, and the nights in summer are too cold and damp for health and comfort, as I know by personal experience of two summers on Nantahala River. But the trout fishing is beyond comparison, and that is one inducement of great value for a stout consumptive who is a good fellow. These mountains are much more broken up into branches, peaks, and spurs than the Cumberlands. They afford no table terrritory of any extent. There are some excellent places there for hot summer visits—Ashville, Warm Springs, Franklin, and others.

The Cumberland Mountains, as a whole, are flat, in broad level spaces, broken only by the "divides," or "gulfs," as they are called by the inhabitants, where the streams flow out into the valleys.

Walden's Ridge, of which we come now to speak particularly, is the best located of any part of the Cumberlands as a place for living. From the separation of this ridge from the main range of Grassy Cove to its southern terminus at the Tennessee River, it maintains a remarkably uniform character in every particular. From it access to commerce is easy, having the Tennessee River and the new (now building) Cincinnati Southern Railroad skirting its entire length on the east. It rises very abruptly from both the Tennessee and Sequatchee Valleys, being from 1,200 to 1,500 feet higher than the valleys on each side. Looking from below, on the Tennessee Valley side, the whole extent of the ridge appears securely walled in at the top by a continuous perpendicular wall of sandstone, from 100 to 200 feet high; and from the Sequatchee side the appearance is very similar, excepting that the wall is not so continuous, and of less height.

The top of the ridge is one level stretch of plain, broken only by the "gulfs" before mentioned and an occasional prominent sandstone wall or bowlder. The width on top is, I should judge, 6 or 7 miles. The soil is of uniform character, light, sandy, and less productive for the ordinary crops of the Tennessee farmer than the soil of the lowlands. The grape, apple, and potato grow to perfection, better than in the valleys, and are all never failing crops; so with rye and buckwheat. Corn grows well, very well in selected spots, and where the land is made rich by cultivation. The grasses are rich and luxuriant, even in the wild forests, and when cultivated, the appearance is that of the rich farms of the Ohio or Connecticut Rivers, only here they are green and growing the greater part of the year; so much so that sheep, and in the mild winters the young cattle, live by the wild grasses of the forests the whole year. The great stock raisers of the Sequatchee and Tennessee Valleys make this the summer pasture for their cattle, and drive them to their own farms and barns or to market in winter. The whole Cumberland table, with the exception of that small part which is under cultivation, is one great free, open pasture for all the cattle of the valleys. Thousands of cattle graze there whose owners never pay a dollar for pasturage or own an acre of the range, though, as a rule, most of the well-to-do stock farmers in the valleys own more or less mountain lands. These lands have, until quite recently, been begging purchasers at from 121/2 to 25 cents per acre in large tracts of 10,000 acres and upward, and perhaps the same could be said of the present time, leaving out choice tracts and easily accessible places, which are held at from 50 cents to $2 per acre, wooded virgin lands.

The forest growth of Walden's Ridge is almost entirely oak and chestnut. Hickory, perhaps, comes next in frequency, and pine after. There is but little undergrowth, and where the forests have never been molested there are but few small trees. This is due to the annual fires which occur every autumn, or some time in winter, almost without exception, and overrun the whole ridge. It does not rage like a prairie fire. Its progress is usually slow, the material consumed being only the dry forest leaves and grasses. The one thing essential to its progress is these dry leaves, hence it cannot march into the clearings. Nearly all the small shrubs are killed by these fires, otherwise they are harmless, and are greatly valued by the stock men for the help they render in the growth of the wild grasses. The free circulation of air through these great unbroken forests is certainly much facilitated by these fires, since they destroy every year what would soon become impediments. The destruction of this undergrowth leaves the woods open, and the lands are mainly so level that a carriage may be driven for miles, regardless of roads, through the forests in every direction.

The shrubs about the fields and places where the forests have been interrupted by civilization and other causes are blackberry, huckleberry, raspberry, sumac, and their usual neighbors, with the azalia, laurel, and rhododendron on the slopes and in the shade of the cliffs.

The kinds of wild grasses, I regret to say, I have not noted, and the same of the rich and varied display of wild flowers.

The whole ridge is well supplied with clean, soft running water, even in the driest of the season. There are no marshes, swamps, or bogs, no still water—not even a "puddle" for long—for the soil is of such a character, that surface water quickly filters away into the sands and mingles with the streams in the gulfs. Springs of mineral water are abundant everywhere. Probably there is not a square mile of Walden's Ridge which does not furnish chalybeate water abundantly. Sulphur springs with Epsom salts in combination are nearly as common.

The entire extent of Walden's Ridge is underlaid with veins of coal, and iron ore is plentiful, especially in the foot hills. The coal and iron are successfully mined in many places on the eastern slope; on the western they are nearly untouched for the want of transportation. I find that the impression prevails that the minerals of the Cumberlands are largely controlled by land agents and speculators. This is only true as applied to a very small part of the whole, not more than 1 per cent. The mineral ownership remains with the lands almost entirely.

The prevailing winds on Walden's Ridge are from the southwest; northers and northeasters are of rare occurrence. One old lady who had resided there for forty years, in answer to my query upon this subject, said: "Nine days out of ten, the year round, I can smell Alabama in the air." This was the usual testimony of the residents. Winds of great velocity never occur there. In summer there is always an evening breeze, commencing at 4 to 6 o'clock, and continuing until after sunrise the next morning. In times of rain, clouds hang low over the ridge occasionally, but they never have fogs there.

The range of the thermometer is less on the Tablelands than in the adjacent valleys. I have had access to the carefully taken observations of the Lookout Mountain Educational Institute, such published accounts as have been made by Professor Safford, State Geologist, Mr. Killebrew, the thorough and painstaking private record of Captain John P. Long, of Chattanooga, and many more of less length of time. From all these I deduce the fact that the summer days are seven or eight degrees cooler on the mountains than in the Tennessee Valley at Chattanooga, and five or six degrees cooler than in the Sequatchee Valley, as far up as Dunlay and Pikeville. The nights on the table are cooler than in the lower lands by several more degrees than the days; how much I have thus far not been able to state. The late fall months, the winter, and early spring are not so much colder than the valleys as the summer months, the difference between the average temperature of the mountains and valleys being at that time four or five degrees less than in the summer. There is no record of so hot a day ever having occurred on the Cumberladd Mountains as to cause mercury to run so high as 95 deg. F., or so cold a day as to cause it to run so low as 10 deg. below zero.

In the average winter the ground rarely freezes to a greater depth than 2 or 3 inches, and it remains frozen but a few days at a time. Ice has been known to form 8 inches thick, but in ordinary winters, 3 or 4 is the maximum. Snow falls every winter, more or less, and sometimes remains for a week. Old people have a remembrance of a foot of snow which lasted for a week.

Walden's Ridge has a total population of a little more than 4,000, scattered over 600 square miles of surface. The number of dwellings is about 800. Ninety per cent. of these are log houses; 70 per cent. of them are without glass windows; light being furnished through the doorways, always open in the daytime, the shuttered window openings, and the open spaces between the logs of the walls. Less than 2 per cent. of these houses have plastered walls or ceilings, and less than 5 per cent. have ceiled walls or ceilings. About 20 per cent. of them are fairly well chinked with clay between the logs, the remainder being but indifferently built in that particular. Fully 90 per cent. of these abodes admit of free access of air at all times of day and night, through the floors beneath as well as the walls and roof above. It is the custom of the people to guard against the coldest of days and nights by hanging bed clothes against the walls, and many good housewives have a supply of tidy drapery which they keep alone for this purpose.

Wood, always at hand, is the only fuel in use. The whole heating apparatus consists in one large open fireplace, built of stone, communicating with a large chimney outside the house at one end, and frequently scarcely as high as the one story building which supports it. This chimney is constructed in such a manner as to be a great ventilator of the whole room, quite sufficient, it would be thought, if there were no other means of ventilation. It is usually made of stone at the base, and that part above the fire is of sticks laid upon one another, cobhouse fashion, and plastered over inside and between with similar clay as that with which the house walls are chinked.

Very few of these houses are more than one story high. They are all covered with long split oak shingles—the people there call them "boards"—rifted from the trunks of selected trees. There is no sheathing on the roof beneath these shingles. They are nailed down upon the flat hewn poles running across the rafters, at convenient distances. Looking up through the many openings in the roof in one of these house, one would think that this would be but poor protection against rain, but they rarely leak.

Not one family in fifty is provided with a cooking stove. They bake their bread in flat iron kettles, with iron covers, covered with hot coals and ashes. These they call ovens. The meat is fried, with only the exception of when accompanied by "turnip greens."

The question, "What is the principal food of the people who live on these mountains?" has been asked by me several hundred times. The almost invariable answer has been, "Corn bread, bacon, and coffee." Occasionally biscuits and game have been mentioned in the answers. All food is eaten hot. Coffee is usually an accompaniment of all three meals, and is drunk without cream and often without sugar. Some families eat beef and mutton for one or two of the colder months in the year on rare occasions, though beef is commonly considered "onfit to go upon," as I was told upon several occasions, and mutton sustains less reputation. Chickens are used for food while they are young and tender enough to fry, on occasions of quarterly meetings, visits of "kinfolks" or the "preachers" and the traveling doctors. Fat young lambs are plenty in many settlements from March to October, and can be had at fifty cents each, but I could not learn that one was ever eaten.

A large majority of the adult population use tobacco in some shape—the men by chewing or smoking, the women by smoking or dipping snuff. They never have dyspepsia, nor do they ever get flesh, after they pass out of childhood, though nearly all the children are ruddy in appearance, and well rounded with fat.

One physical type prevails among the people in middle life, and carries along into old age but little change; and old age is common there. Nearly every house has its old man or old woman, or both. Everybody, father and mother, and frequently grandfather and grandmother, is still on hand, looking as brisk and moving about as lively as the newer generations. After they pass their forty years, they never seem to grow any older for the next twenty or thirty, and the grandfathers and grandmothers can scarcely be selected, by comparison, from their own children and grandchildren. The men are taller than the average, and the women, relatively, taller than the men. They are all thin featured, bright eyed, long haired, sharp looking people, with every appearance of strength and power of endurance.

I think the men who live on Walden's Ridge can safely challenge the world as walkers—aborigines and all; and unless the challenge should be accepted by their own women folks, I feel quite sure they would "win the boots." They go everywhere on foot, and never seem to tire.

Nearly all the people of the Tablelands are employed in the pursuits of agriculture. Very few of them seem to be hard workers. The men are all great lovers of the forest sports, much given to the good, reliable, old fashioned long rifles. The women and children are much employed in out door occupations, and live a great portion of their time in the open air. The clothing of all classes is scanty. The use of woolen fabrics for underwear has not yet been introduced, and coarse cotton domestic is the universal shirting, and cotton jeans, or cotton and wool mixed, constitute the staple for outer wearing apparel. The men wear shoes throughout the year much more commonly than boots. They never wear gloves, mittens, scarfs, or overcoats, and they scorn umbrellas. Probably this whole 4,000 people do not possess two dozen umbrellas or twice as many overcoats. The women go about home with bare feet a great part of the summer. They never wear corsets or other lacing.

I have learned by careful inquiry that very few of the people of the Ridge have ever had the diseases of childhood. Scarlet fever I could hear of in but two places, and I suppose that not one person in fifty has had it. Whooping cough and measles have occurred but rarely, and the large majority have not yet experienced the realities of either. Very few people there have ever been vaccinated, nor has smallpox ever prevailed. Typhoid, typhus, and intermittent fevers are unknown. In the great rage of typhoid fever which took place ten or twelve years ago in the Tennessee and Sequatchee Valleys, not a single case occurred on the Mountains, as I have been informed by physicians who were engaged in practice in the neighborhood at the time. Diphtheria has never found a victim there; so of croup. Nobody has nasal catarrh there, and a cough or a cold is exceedingly rare.

I have said that these observations refer more particularly to Walden's Ridge than to the Cumberland Tablelands in our State as a whole. This ridge was chosen by me for this examination, mainly for the reason of its convenience, but partly owing to its being more generally settled than any other equal portion of the table which lies in Tennessee. Lookout Mountain is not as well located; it is on the wrong side of the Tennessee River, and but a few acres of it belong in this State. Sand Mountain is altogether out of the State, but it is perhaps nearer like Walden's Ridge in its physical features than Lookout. That part of the Cumberlands west of Sequatchee Valley is Walden's Ridge in duplicate, excepting that it is further west, and nearer the Middle Tennessee basin. There are some small towns, villages of miners, and summer resorts there, which interferes with that evenness of the distribution of population which Walden's Ridge has, rendering it more liable to visitations of epidemic and contagious diseases. The tablelands north of the center line of the State, above Grassy Cove, are very similar to Walden's Ridge, as far up as Kentucky, with the exception before mentioned—that of climate—it being from one to ten degrees colder in winter.

This whole Cumberland Table is no small country. It comprises territory enough to make a good sized State. At present, it is almost one great wilderness, in many particulars as unknown as the Black Hills. It is coming into the world now, and will be well known in a few years. The great city of Cincinnati has determined to build a railroad through the very center of this great table in the north part of the State, connecting with Chattanooga in the southern part. This road is nearly bored through, and in another year or two the Cumberland Tablelands in Tennessee will be much heard of at home and abroad.

It seems to me this country has merits. It is located in the latitude of mild climate; not so far south as to be scorched by the hot summer sun, or visited by the great life destroying epidemics; not so far north as to meet the severe and lengthened winters.

Climate, we know, is a fixture; it has a government; it has rules; the weather may change, but climate does not; it is a permanent out-door affair, and what is true of to-day was true centuries ago, and will be true forever, in the measure of any practical scope, at least. The people of the world are beginning to know that the greatest destroyer of human life has its remedy in climate.

Mr. Lombard, in his famous exhibit in relation to the prevalence of consumption among the people of different occupations, circumstances of life, and place of dwelling, gives the lowest number of deaths from this cause to those who live in the open air. He found the people who lived most in the open air, as would be readily conjectured, in the mild latitudes, not in the countries of hot sands or cold snows.

[The above article, in regard to which we have noticed frequent allusions in many of our exchanges, all erroneously attributing it to Dr. Wright, of Tennessee, and for which we have received repeated requests quite recently, was read by the lamented Dr. E.M. Wight at the 43d annual meeting of the Tennessee State Medical Society, held at Nashville, April 4, 5, and 6, 1876. Its distinguished and talented author will long be remembered as one of the most active, earnest, and zealous members of the State Society. At this meeting he also read a very admirable paper on "The Microscopic Appearance of the Blood in Syphilis," and prepared the report of the Committee on State Board of Health, to which report may be ascribed the honor of securing the necessary legislation organizing the Board. A true, upright, honest man, an earnest, devoted and zealous physician, universally esteemed and beloved by all who knew him; himself the subject of tuberculosis, dying in the prime of a brilliant manhood. He had but few equals in the glorious profession he honored and loved so well.

From a careful reading of his paper, we find that he describes a large area of territory, free, absolutely free, from subsoil moisture, a climate mild and equable, a soil capable of producing nearly everything necessary for the comfortable maintenance of human life, surroundings that tempt, nay, compel the greatest possible amount of open air life. His description is exceedingly accurate of a plain, primitive, simple-minded people with but few wants, many of the virtues and few of the vices of humanity. With their surroundings, soil, climate, residence, and mode of living, need we be surprised that "there is a people," or a land "free from consumption"?—ED.]—Southern Practitioner.

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THE TREATMENT OF HABITUAL CONSTIPATION.

Dr. F.P. Atkinson thus writes in the Practitioner, January, 1884: I suppose there is no derangement of the system we are more frequently called upon to treat than habitual constipation; and though all kinds of medicines are suggested for its relief, they rarely produce more than temporary benefit—and it is difficult to see how the result can well be otherwise, while the root of the evil remains untouched. Now by far the more numerous subjects of this disorder are women; and as they do not seem to know that regularity is essential to the performance of every one of nature's operations, they appoint no stated times for trying to get the bowels relieved, but trust to receiving intimation when the rectal accumulation and distension can be borne no longer. This method of action may and does answer fairly well for a time; but nature gradually gets upset, the sensation of the lower bowel becomes blunted, and at last it ceases to respond to the ordinary stimulus. Then aperients are regularly resorted to, and although these act fairly well for a time, they gradually have to be increased in strength and frequency. Now, as regards the treatment, the first thing to be accomplished is of course to get the rectum well relieved; the next, to get the actions to take place at fixed times; and lastly, it is necessary to get more tone imparted to the muscular tissue of the bowels, so that the regularity of action may be helped and also maintained. In order, then, to get the bowels relieved in the first instance, it is well to give five grains of both compound colocynth and compound rhubarb pill at bed-time (this rarely requires to be repeated), then to take a tumblerful of cold water the next morning on waking, and repeat it regularly at the same time each day. Should the bowels remain sluggish for some time, the same quantity of water may be taken daily before each meal. Supposing no action takes place on rising or shortly after, a small injection of warm water may be resorted to. After each movement of the bowels, a small hand-ball syringeful of cold water should be thrown into the rectum and retained. A soup plateful of coarse oatmeal porridge (made with water and taken according to the Scotch method, viz., by filling half the spoon with the hot porridge and the other with cold milk) each night at bed-time, or even every night and morning for a time, is often a very great help. But above all things, it is necessary for the patient to try and get relief at a certain fixed time regularly every day. If these directions are strictly carried out in their entirety, the evil, even if it has been of long standing, will generally be corrected, and the patient will improve in health and appearance. Of course where the constipation results from exhaustion of the nervous system (such, for instance, as is brought about by self-abuse), the special cause has to be taken into consideration, and such treatment adopted as is suited to the particular necessities of the case.

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THE PYRAMIDS OF MEROE.

About fifty miles from the mouth of the Atbara, and, of course, on the eastern bank of the Nile, stand the pyramids of Meroe. They consist of three groups, and there are, in all, about eighty pyramids. The presumption is that they represent the old sepulchers of the kings of Meroe. Candance, Queen of the Ethiopians, mentioned in Acts, chap. viii., v. 27, is supposed to have belonged to Meroe, that being the name also of the capital, which is understood to have been somewhere not far distant from the sepulchers. These pyramids of Meroe possess one marked feature, distinguishing them from the pyramids of Egypt proper—that is, they have an external doorway or porch. As there is no entrance to the pyramid at these porticoes, it is quite possible that they were temples for worship or making offerings to the dead. By comparing them with the pyramids of Ghizeh, it will be seen that they are also taller in proportion to their base. Another important point in these porches or temples is the existence of the arch; and that, too, an arch in principle, with a keystone.—Illustrated London News.



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THE PROLIFICNESS OF THE OYSTER.

In an article by Prof. Karl Mobius on "The Oyster and Oyster Culture," reproduced in the recently issued report of the U. S. Commissioner of Fish and Fisheries, the author says:

A mature egg-bearing oyster lays about one million of eggs, so that during the breeding season there are upon our oyster beds at least 2,200,000,000,000 young oysters, which surely would suffice to transform the entire extent of the sea-flats into an unbroken oyster bed; for if such a number of young oysters should be distributed over a surface 74 kilometers long by 22 broad, 1,351 oysters would be allotted to every square meter. But this sum of 2,200,000,000,000 young oysters is undoubtedly less than that in reality hatched out, for not only do those full-grown oysters which are over six years of age spawn, but they begin to propagate during their second or third year, although it is true that the young ones have fewer eggs than those which are fully developed. At a very moderate estimation, the total number of three to six year old oysters which lie upon our beds will produce three hundred billions of eggs. This number added to that produced by the five millions of full grown oysters would give for every square meter of surface not merely 1,351 young oysters, but at least 1,535. In order to determine how many eggs oysters produce, they must be examined during their spawning season. This begins upon the Schleswig-Holstein beds in the middle of June, and lasts until the end of August or beginning of September. The spawning oyster does not allow its ripe eggs to fall into the water, as do many other mollusks, but retains them in the so-called beard, the mantle, and gill-plates until they become little swimming animals. The eggs are white, and cover the mantle and gill-plates as a semi-fluid, cream-like mass. As soon as they leave the generative organs the development of the germ begins. The entire yolk-mass of the egg divides into cells, and these cells form a hollow, sphere-like body, in which an intestinal canal arises by the invagination of one side. Very soon the beginnings of the shell appear along the right and left sides of the back of the embryo, and not long afterward a ciliated pad, the velum, is formed along the under side. This velum can be thrust out from between the valves of the shell at the will of the young animal, and used by the motion of its cilia as an organ for driving food to the mouth, or in swimming as a rudder. During these transformations the original cream-white color of the germ changes into pale gray, and finally into a deep bluish-gray color. At this time they have a long oval outline, and are from 0.15 to 0.18 of a millimeter in breadth. Over 300,000 can find room upon a square centimeter of surface. If an oyster in which the embryos are in this condition is opened, there will be found upon its beard a slimy coating thickly loaded with grayish-blue granules. These granules are the embryo oysters, if a drop of the granular slime be placed in a dish with pure sea water, the young animals will soon separate from the mass, and spread swimming through the entire water. When the embryos are at this stage their number may be estimated in the following manner: The whole mass of embryos is carefully scraped from the beard of the mother oyster by means of a small hair brush. The whole mass is then weighed, and afterward a small portion of the mass. This small portion is then diluted with water or spirits of wine, and the embryos portioned out into a number of small glass dishes, so that they can be placed under the microscope and counted. Thus, knowing the weight of the small portion and the number of embryos in it by count, we can estimate the total number of embryos from the weight of the entire mass, which is also known. In this manner I estimated the number of embryos in each of five full grown Schleswig-Holstein oysters caught in August, 1869, and found that the average number was 1,012,956.

Notwithstanding this great fecundity, but an extremely small proportion of the young oysters produced during the course of the summer arrive at maturity, 421 only out of 500,000,000 escaping destruction. The immolation of a vast number of young germs is the means by which nature secures to a few germs the certainty of arriving at maturity. In order to render the ideas of germ-fecundity and productiveness more easily understood, Prof. Mobius makes the following comparison between the oyster and man:

According to Wappaus, for every 1,000 men there are 347 births. According to Bockh, out of every 1,000 men born 554 arrive at maturity, that is, live to be twenty years or more of age; thus, on an average, 347 children are produced from 554 mature men, or 626 children from 1,000 mature men. Since 1,000 full-grown oysters produce 440,000,000 of germs, then the germ fecundity of the oyster is to the germ fecundity of man as 440,000,000 to 6.26, or as 7,028,754 to 1. On the other hand, the number which arrive at maturity is 579,002 times as great with mankind as with the oyster; for of 1,000 human embryos brought into the world 554 arrive at maturity, or of 440,000,000 newly born 243,760,000 would live to grow up, while of 440,000,000 young oysters only 421 ever become capable of propagating their species. The proportion is then 421 to 243,760,000, or as 1 to 579,002. I am fully persuaded that these figures represent the number of oysters which arrive at maturity more favorably than is really the case, since from every thousand of full grown oysters it is certain that, on an average, more than 440,000,000 young are produced.

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RED SKY.

The beautiful red sky which has been so frequent of late, morning as well as evening, has excited much comment. The comment, however, has consisted more of description, statement of fact, theory, and wonder as to cause, rather than as to satisfactory explanation.

Facts in the case which would reveal the secret of this beautiful display of nature are not complete and numerous enough at present to establish the cause of this phenomenon on a sure basis; yet enough facts, it would seem, have been obtained to satisfy the strong mind capable of bridging over a wide expanse.

Facts in an argument are like piers to a bridge-the more we have of them, c. p., the more substantial the structure. When the facts are legion, the structure becomes a causeway, and there is no need of argument.

Argument is a bridge—the fewer the facts, the more the necessity for the bridge; the less the facts, the more argument necessary to connect the few we have, and the more skill is required to make substantial connecting links between the few solid piers (facts) that exist.

One of the queer things in connection with this is, the public have looked chiefly, if not wholly, to the astronomers for an explanation of this phenomenon, when it is not their special province to explain matters in this department of nature.

The explanation belongs to the department of meteorology, and not to astronomy. But the fact of having looked to the astronomers shows how little the world knows of meteorology and how few meteorologists there are able, ready, and willing to rise and explain in face of the opposition of the public, who seem to think that the explanation must necessarily belong to astronomy. Astronomy proper deals with the position of the earth in space and its relation to the other heavenly bodies, whether suns, fixed stars, planets, satellites, comets, or other bodies in the vast space about us. Meteorology deals with the atmosphere of the globe, in all its forms. Astronomy could be studied in the early ages; its grand facts were not wholly dependent upon the advanced condition of the mechanic arts; it could be studied even without the aid of telescopes, though telescopes have added much to its advancement. Meteorology, on the contrary, depended on the advancement of the arts and sciences; they must first be perfected ere we could know much about this branch of science. To one unfamiliar with the advancement and perfection of meteorology within the past ten years, this statement may seem strange, yet it is an undisputable fact that, prior to the establishment of the daily weather reports, the knowledge on this subject amounted to very little, and was not even worthy of being designated a science. Prior to the advent of the weather map the world was in absolute ignorance of the laws governing the atmosphere. Sure, we had had large volumes on the laws of storms, but the later revelations leave them shelved high and dry on the shores and as useless as a wreck in a similar condition; with the daily weather map before us we have no need to even open these huge volumes; they are completely circumvented, and only negative in value—to show how little was known of the subject without the full and complete facts daily collected and spread before us on the map published by the Weather Bureau.

In order to understand the color of our sky, we must understand the subject which is so immediately connected with it and its creation.

The earth is a sphere in space; generally speaking, it is composed of land and water. These are two factors; the heat that it derives from the sun forms a third factor; the three—land, water, and heat—are essential to life, at least the higher conditions of life which culminate in man. The old physical geography taught us this much, but it was not able to go further and tell us why it was cold or warm independent of the seasons; it could not explain why it was at times as warm, and even warmer, half-way to the pole than at the equator; why it was at times very warm in the extreme northeast while very cold in the Southern States; cold in the northwest when it was warm in the northeast, and warm in the northwest when cold all along the upper Atlantic seaboard; it could not forewarn us of storms. These and a host of other facts, which the weather map makes as plain as astronomy demonstrates that Jupiter is a planet, the new revelation, through the instrumentality of the perfected telegraph system, makes exceedingly plain to us if we will but seek the easily obtained information.

The principal revelations of the weather map are the facts in regard to the areas of high and low barometer, and the influence they exert upon the climate of the globe.

These conditions—high and low barometer—move on general lines from the west towards the east, or towards the rising sun, and around the world in irregular belts. The centers of low barometer are various distances apart, from a thousand to two thousand and even more miles apart—call the average about two thousand miles.

The clouds are formed from the moisture present by the action of the sun's heat. The direction of the wind is from the area of high barometer to that of low. The nearer the winds approach the center of "low" (low barometer), the more they partake of the lines of the volute curve, or curve of the sea shell or water in a whirlpool. High barometer is the atmospheric hill; low barometer is the atmospheric valley. But time at present will not permit more than these general statements; a close study of the weather map for a season will reveal the beautiful minor details.

To the reader it may seem a long way round, yet in order to fully understand the nature of the atmosphere which surrounds our globe we must pay due attention to these newly discovered physical laws.

The red sky which was so noticeable, in the fall of 1883, the astronomers have told us was due to "meteoric dust" which was produced by the volcanic eruption on the island of Java, August 27, 1883.

This "meteoric dust" they say combined with the atmosphere, followed it around the earth, and caused the beautiful redness of the sky at morning and evening. For one, I do not believe dust of any description in the atmosphere would produce such an effect.

There is nothing luminous, transparent, or delicate about dust. Dust would not remain in the atmosphere for months, it would settle in a very short time, and if thick enough in the atmosphere to obstruct the light of the sun it would be visible, discernible, to the eye, and manifest on the face of nature. Years ago, before the age of the weather map, we might have thought that the atmosphere followed the surface of the earth like the water on a grindstone, but it does not. As already seen, the wind is from the area of high barometer to that of low, and there are many of these "low centers."

From the best calculation we can make at present, there would be at least some six centers on an average between the center of the United States and the island of Java. In addition to this there would also be a number of belts of "low" centers, which would complicate the thing threefold at least. At all these different centers the winds would be blowing from all points of the compass at the same time. Such winds would not be apt to bring the "meteoric dust" from Java to the United States, either in an easterly or westerly direction. But, it is said, "dust" has been gathered.

How high from the surface of the ground has this dust been gathered—at what elevation?

There is undoubtedly a little dust in the air most of the time, but I do not think that it extends very high. Where it would be the highest and most perceptible would be on the arid plans of Africa and Asia, when the simoom is passing, or in the track of a tornado. But from the multiplicity of these storm centers and the varied winds they would produce even this dust could not travel from Java to America.

Again, all clouds, no matter how high or how low, are affected by the low centers, as the movement of clouds prove, and travel from the "high" to the "low," from and to all points of the compass. High authority gives the heights of the clouds as follows: lower clouds, 16,000 feet; upper clouds, 23,000 feet.

As all clouds, from the highest to the lowest, are affected by the centers as above referred to, it follows that if this "meteoric dust" follows the earth around, as it would have to do in order to make good this theory, it would have to travel suspended in the atmosphere above the upper clouds, or at a height of more than 23,000 feet, or at an elevation of over four miles!

Now, is it reasonable to believe that dust, however fine, will remain in the atmosphere at that elevation for over six months?

As a side argument it is suggested that the smoke of the burning woods, or few years ago in Michigan, caused as peculiar condition of the atmosphere. This extensive fire was on a day when the area of low barometer was on a high line of latitude and passing to the eastward. This naturally took the smoke, which is far lighter than dust, along with it. It mingled with the muggy condition of an extensive "low," and produced a yellowness of the atmosphere. This however was of only a few hours' duration, and was only visible in favorable localities.

Here again we see the advantage of the weather maps; but for this map we would never have been able to have satisfactorily explained the peculiar phenomenon produced by the great Michigan fire.

If the delicate redness of the sky is not caused by dust, what is it caused by?

But for the weather map, I think we should still be in the dark in regard to it.

In the first place, this redness is nothing new, only the conditions are more favorable sometimes than at others. It has always existed and always will exist, independent of earthquakes, volcanoes, etc. Nature is ever changing; the movements of the atmosphere more resemble the kaleidoscope than any thing else.

The summer and fall of 1883, the movements of "high" (high barometer) over the United States were quite central and extensive, causing this peculiar phenomenon over a wide extent of territory.

We have no information of the condition of the barometer over the other part of the world; we speak move particularly of the United States; yet if certain conditions produce certain effects here, it is quite safe to say that the same effects are produced by the same cause elsewhere.

As now well established by the map, the surface wind is from the area of high barometer to that of low—from the atmospheric hill to the atmospheric valley.

The tendency of this is to free "high" of all clouds and moisture; but then it is impossible to free "high" entirely of moisture; a little will remain, and it is just this little, which is highly rarefied, that produces the result. We look around us and above, we see little or no evidence of evaporation, yet it is the while going on. When the sun is immediately below the horizon, where it will shine horizontally through the mass of light, suspended moisture, the delicate presence of vapor heretofore unnoticed is revealed. The action of the sun's rays is the same as when illuminating a well formed cloud—it is an embodiment of the same principle, but the material is much more expanded. The particles of suspended moisture are very fine, few and far between, therefore the effect of the light upon it is more diffused and transparent. It is much like looking through a piece of window glass flatwise and endwise; flatwise we do not perceive any color; endwise, from seeing through a greater mass, the glass has a very perceptible green color.

We see the same idea also in the rising and setting sun and moon. On a clear, cloudless night, when nothing seems to interfere with the brightness of the stars, we cannot, by looking upward, perceive any moisture present in the atmosphere; but if we cast our eyes to the horizon, whereby we see through the mass of atmosphere endwise, as it were, and note the appearance of the stars there, or the rising or setting moon, we will see that the atmosphere there gives a redness to the rising body, which it does not have when it has ascended to mid-heaven. On a clear night, which is caused by the presence of the area of high barometer, the moon when in mid-heaven is of a clear, silver-white, and it is the same moon that at the horizon was a deep red. The color of the moon has not changed; it is simply the medium through which it is seen that produces the difference in color.

Occasionally, on a clear, bright ("high") night, when the moon is full, prior to rising, when just below the horizon, it will so illuminate this lower strata of atmosphere as to appear like a great fire; the moon rises red, but its deep color gradually fades as it rises, and when well up in the heavens we perceive that this deep coloring was an illusion and merely the influence of its surroundings. I never, though, knew of any one to attempt to account for this by "meteoric dust;" and yet it is an embodiment of the same principle. Place the sun where the moon is, and from its far superior abundance of light we have a much grander display.

Under no other conditions or relations of the sun and earth is it possible to have this phenomenon of the delicate red sky but when a positive area of high barometer is passing and extends over us. In order to produce this effect we must have the clear atmosphere of high barometer, when there is a minimum of moisture present. The action of the sun's rays upon this extensive area of slightly moist rarefied air is unconfined by clouds, and reaches far and wide, and produces a delicacy of color which from no other source or condition can be realized.

ISAAC P. NOYES.

Washington, D. C., 1884.

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A THEORY OF COMETARY PHENOMENA.

To the, Editor of the Scientific American:

The following subject, substantially, was written more than a year ago with a view to its publication. It was not, however, until January of the present year that I sent a brief communication to the Brooklyn Eagle, which was published Feb. 3, giving my views in relation to cometary phenomena. With this I might remain satisfied, were it not that the interesting paper by G. D. Hiscox, published in the SCIENTIFIC AMERICAN SUPPLEMENT, Feb. 16, impressed me with the idea that the theory I advanced might assist in explaining others, if brought to the notice of those interested through the columns of your valuable journal.

The theory that I advance to account for the several phenomena relating to comets' tails is, that comets are non-luminous, transparent bodies; that they transmit the light of the sun; that the transmitted light reflected by the particles of matter in space constitutes the tails of comets. "Like causes produce like effects." By contraries, then, like effects must be produced by similar causes; for, if an effect produced by a cause which is known is similar to an effect produced by a cause which is not known, the cause which is known must be similar to the cause which is not known. This is true or not.

I submit the following experiments to substantiate the theory advanced.

Partially fill a vial or a tumbler with water, hold it by the rim, and move it around a lighted candle placed upon a table. A shadow surrounding the transmitted light will be cast upon the table. As the tumbler approaches the light, the shadow follows the tumbler, and when receding the tumbler follows the shadow; and as the tumbler is moved around the light, the shadow will swing round from one side to the other. If the tumbler be held so that a puff of smoke can be blown into the transmitted rays, the particles of smoke will reflect the transmitted light, and will illustrate my idea of what constitutes a comet's tail. A dark band may be observed in this stream of light, as also in the light cast upon the table.

In these experiments, we see the effects produced by a cause which is known; the effects are similar to those observed in the tails of comets, the cause of which we do not know; but is it not reasonable to assume that the cause is similar?

Assuming now that comets are transparent, can any other phenomena peculiar to comets be accounted for upon this hypothesis? Next to the tail itself, the curve is the most noticeable feature, and if we consider the extraordinary length of these appendages, the astounding velocity at which comets move in their orbits, and the time that would elapse before a ray of light, emitted from the nucleus, would reach the end of the tail, perhaps the curve—which, if I am not deceived in my observations, always dips toward its orbit—can be accounted for. If a comet moved in a direct line toward the center of the sun, there would be no curve to the tail. But taking Donati's comet of 1858 as an example, the tail of which was said to be about 200,000,000 miles long, a ray of light traveling at the rate of 192,000 miles per second would be about twenty minutes in going from the nucleus to the end of the tail.

But during that time the comet would move in its orbit, say, 50,000 miles, and as light moves in a straight line, and other rays are constantly emerging from the nucleus as it moves along in its course, the result is that the tail has a curved appearance.

I have no data at hand regarding this comet, but what I have said will serve to illustrate my ideas. Again, referring to this comet, I remember to have read the statement of an astronomer that, after passing round the sun, a new tail was formed opposite the original one. Now, it seems to me that that is just what would happen, for in moving round the sun the comet would travel say 3,000,000 miles; the greater portion of the tail then, would extend millions of miles upon one side of the sun, while from the nucleus upon the opposite side of the sun a new tail would appear to be formed.

Upon this hypothesis, the extraordinary length of their tails and the fact that stars are visible through the densest portion of them is explained; as also the fact that they so rapidly disappear from view when moving from the sun, the light received by them from the sun being in proportion to their distance from it, and but little of that reflected.

JOHN M. HUGHES.

Brooklyn, N. Y.

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[FOR THE SCIENTIFIC AMERICAN.]



ON COMETS.

When we see a comet approaching the sun with its tail following in the orbit of the nucleus, we have no great difficulty in believing the common theory that a comet consists of nucleus attracted toward the sun, while the tail is repelled; and that we see the whole of it. But as it approaches the sun, difficulties arise that make us doubt whether the theory be true.

Let us suppose a comet with a tail 50,000,000 miles in length, and that it will require two days to pass round the sun. Now the tail, being always in a line drawn through the center of the sun and center of the nucleus, will, when it reaches the long axis of the elliptical orbit, stand perpendicularly to the orbit of the nucleus. That is, the extremity of the tail farthest from the sun, in addition to its onward motion, has acquired a lateral motion that has lifted it 50,000,000 miles in the first day of its perihelion. The velocity of the extremity has been vastly accelerated over that of the nucleus, and it has moreover a sheer lift above the orbit of the nucleus. Now this lift is in opposition to gravity; neither is it in consequence of any previous momentum, for its velocity is accelerated and its previous momentum would be a hindrance; nor is the lift in consequence of any repelling force from the sun, for such force would be diminished in proportion to the square of the distance, and the far end would be acted on less than the nucleus end of the tail, whereas the velocity of the former is increased a hundred fold over that of the latter. A polar force in the comet would merely draw the comet into the sun. We therefore find no force adequate for such a lift, but on the contrary all the forces are opposed to it.

But if the first day of the perihelion overwhelms us with difficulty, the second day will prove disastrous to the common theory. For the extremity of the tail farthest from the sun will be required to pass with lateral motion from its perpendicular 100,000,000 miles, so that it may be in advance of the nucleus and again rest on its orbit. This orbit is an impassable line, and therefore instantly arrests the prodigious lateral velocity of the tail. That impassable orbital line is to it as solid and inflexible as a wall of adamant. The motion so instantly arrested would be disastrous to any tail, whether composed of gas, meteorites, or electricity, whatever that may be.

Having shown that the common theory of comets is filled with insuperable difficulties, I will again call attention to a theory proposed about eighteen months ago in the SCIENTIFIC AMERICAN.

According to this theory, a comet consists of a nucleus and an atmosphere, for the most part invisible, surrounding it on all sides to an extent at least equal to the length of the tail. The rays of the sun in passing through or near the nucleus are so modified as to become visible in their further progress through the cometic atmosphere, while all the rest remain invisible. What we call the tail is merely a radius of the cometic atmosphere made visible, and as the comet moves through space, only different portions of the atmosphere come in sight, in obedience to the ordinary laws of light. There is no difficulty in accounting for the rise and fall of the tail at perihelion, nor for the tail preceding the nucleus afterward.

The spherical theory accounts easily for the different forms of tail seen in different comets. The sword shaped tails, at variance with the common theory, can be accounted for by supposing a slight difference in density or material in the cometic atmosphere, which will deflect the light as seen. The comet of 1823, which cannot be explained on the common theory, is very easily explained on the spherical. That comet showed two tails, apparently of equal length, which moved opposite to each other, and perpendicularly to the orbit of the nucleus, and showing no signs of repulsive force from the sun. On the spherical theory it is only necessary to suppose such an arrangement of the nucleus as would reflect the rays of the sun laterally; a slight modification of the nucleus would give not only two but any number of tails pointing in different directions.

It may be objected to the spherical theory that a tail 50,000,000 miles long would call for a sphere 100,000,000 miles in diameter, and that would be too vast for our solar system. But it is claimed for this sphere that it consists of the same material as the so-called tail, and that it has the same capability of moving among planets without manifest disturbance to either.